As a top coat composition, various fundamental requirements as weather resistance, chemical resistance and appearance of the coating and interlaminar adhesion and recoatability of the composition must be cleared out. Recently, in the automobile and other industries, public attention has been paid to the coating on plastic material. At that time, improved bending and adhesion properties sufficient enough to be tolerable to the processing conditions are in fact required for the top coat made of the said coating composition.
Heretofore, as a top coat for automobile bodies, an alkyd resin base composition has been widely used because of its excellent flowing properties and good appearance of the coating. However, there are problems, in that it has in such paint, of poor chemical resistance as poor acid resistance, such and alkaline resistance. Though an oil-free polyester resin is excellent in chemial resistance, the coating formed is poor in flowability and hence in appearance, and therefore, such resin has hardly been practically used as a top coat vehicle in the related field.
It is, therefore, an object of the invention to provide a polyester resin composition which is specifically useful as a resinous vehicle in a top coat composition and capable of resulting in a coating with excellent chemical resistance, interlaminar adhesion, recoatability, weather resistance and flexibility, as well as the predominant properties of an alkyd resin as flowability and film appearance.